Anthraquinone compounds and polarizing film containing the same

ABSTRACT

An anthraquinone compound represented by formula: ##STR1## wherein R and X are as defined in the specification, and a polarizing film containing the same. The anthraquinone compound exhibits satisfactory compatibility with organic polymers and high dichroism, and the polarizing films have excellent performance characteristics.

PRIOR APPLICATION

This application is a divisional of U.S. patent application Ser. No.143,366 filed January 12, 1988 now U.S. Pat. No. 4,891,057, which claimsthe priority of Japanese Applications 5569/87 and 28696/87, filedJanuary 13, 1987 and February 10, 1987, respectively.

FIELD OF THE INVENTION

This invention relates to a novel anthraquinone compound and apolarizing film containing the same.

BACKGROUND OF THE INVENTION

Conventionally known polarizing films include polyvinyl alcohol (PVA)base films dyed with iodine or a dichroic dye. Since these polarizingfilms, though exhibiting excellent polarizing performance, are inferiorin heat resistance, moisture resistance, and the like, an acetylcellulose film or the like film has been laminated thereon for practicaluse. Nevertheless, the laminated polarizing films still haveinsufficient moisture resistance depending on use.

Polarizing films comprising, as a film base material, a hydrophobicpolymer other than PVA have been proposed, in which a vinyl halidepolymer, e.g., polyvinyl chloride (PVC), polyvinylidene chloride (PVDC),etc., is dehydrohalogenated to form a polyene structure. However, theyhave not yet become so popular not only because they are alsounsatisfactory in stability to heat, light or oxygen but because a freechoice in hue is not allowed.

Further, polyamide base polarizing films have also been proposed asdisclosed in Japanese Patent Publication No. 3944/74 and Japanese PatentApplication (OPI) No. 45153/79 (the term "OPI" as used herein means"unexamined published Japanese patent application"). Although thepolyamide-dye type polarizing films are superior to PVA-iodinepolarizing films, PVA-dichroic dye polarizing films, or polyene typepolarizing films in terms of heat resistance, moisture resistance,dynamic strength, and the like, they are inferior in polarizingperformance to these three types of polarizing films.

SUMMARY OF THE INVENTION

One object of this invention is to provide a novel anthraquinonecompound having satisfactory compatibility with an organic polymer andhigh dichroism.

Another object of this invention is to provide a polarizing film havingexcellent characteristics, such as polarizing performance, heatresistance, moisture resistance, weather resistance, transparency, andthe like.

The present invention relates to an anthraquinone compound representedby formula (I) shown below and a polarizing film containing the same.

Formula (I) is represented by ##STR2## wherein two R, which may be thesame or different, each represents a hydrogen atom, --NHCOR¹, --CONHR¹,or ##STR3## wherein R¹ represents an alkyl group, a substituted orunsubstituted aryl group, or a substituted or unsubstituted cycloalkylgroup; ring A represents a substituted or unsubstituted aromatic oraliphatic ring; and two X, which may be the same or different, eachrepresents a hydrogen atom or an amino group, provided that X and R arenot simultaneously a hydrogen atom.

DETAILED DESCRIPTION OF THE INVENTION

In formula (I), the alkyl group as represented by R¹ preferably includesa straight chain or branched alkyl group having from 1 to 8 carbonatoms. The substituted or unsubstituted aryl group as represented by R¹includes a phenyl group; a phenyl group substituted with an alkyl group,and preferably an alkyl group having from 1 to 8 carbon atoms; a phenylgroup substituted with an alkoxy group, and preferably an alkoxy grouphaving from 1 to 8 carbon atoms; a biphenyl group, a heterocyclic group,e.g., a pyridinyl group, etc.; a naphthyl group, an anthraquinon-2-ylgroup; a phenyl group substituted with an acylamino group, such as analkylcarbonylamino group (e.g., an acetylamino group, a butyrylaminogroup, a caprylamino group, etc.), and an arylcarbonylamino group (e.g.,a benzoylamino group, a p-butylbenzoylamino group, ap-phenylbenzoylamino group, etc.); a 4-cyclohexylphenyl group; acyclohexylphenyl group substituted with a trans-4-alkyl group, andpreferably an alkyl group having from 1 to 8 carbon atoms; and the like.The substituted or unsubstituted cycloalkyl group as represented by R¹includes a cyclohexyl group, a 4-alkylcyclohexyl group, and preferably atrans-4-alkylcyclohexyl group substituted with an alkyl group havingfrom 1 to 8 carbon atoms, a 4-cyclohexylcyclohexyl group, etc.

The group of ##STR4## includes aromatic or aliphatic cyclic imidogroups, such as ##STR5## wherein Z represents a halogen atom (e.g., achlorine atom, a bromine atom, etc.); and n represents an integer offrom 1 to 4, ##STR6## wherein R² represents --COOR³, wherein R³represents an alkyl group, and preferably an alkyl group having from 1to 8 carbon atoms, --CONHR³, ##STR7## wherein R⁴ represents a hydrogenatom, an alkoxy group having from 1 to 8 carbon atoms or R³, ##STR8##

The anthraquinone compounds represented by formula (I) can be prepared,for example, by reacting an anthraquinone compound represented byformula (II) ##STR9## wherein X is as defined above, with a compoundrepresented by formula (III)

    Y--CO--R.sup.1                                             (III)

wherein R¹ is as defined above; and Y represents a halogen atom (e.g., achlorine atom, a bromine atom, etc.), or a compound represented byformula (IV) ##STR10## wherein ring A is as defined above, in a solvent,such as an aromatic solvent (e.g., mono-, di-, or trichlorobenzene,nitrobenzene, etc.), an amide solvent (e.g., N,N-dimethylformamide,N-methylacetamide, N-methylpyrrolidone, etc.), and the like, at atemperature, for example, of from 50° to 200° C.

The reaction between the compound of formula (II) and the compound offormula (III) may be carried out in the presence of an acid scavenger,such as alkylamines (e.g., triethylamine, tributylamine, etc.),nitrogen-containing compounds (e.g., pyridine, picoline, quinoline,quinaldine, etc.), and inorganic bases (e.g., potassium carbonate,sodium carbonate, sodium hydrogencarbonate, potassium hydroxide, etc.).

Alternatively the anthraquinone compounds represented by formula (I) canbe prepared, for example, by reacting 1,5-dichloroanthraquinone with acompound represented by formula (V) ##STR11## wherein R is as defined informula (I), in an amide solvent such as N,N-dimethylformamide,N-methylacetamide, N-methylpyrolidone, etc. in the presence of theaforementioned acid scavenger at a temperature of from 50° to 200° C.

The organic polymers which can be used as a film base material for thepolarizing films of the present invention include polyester,polycarbonate, polyethersulfone, polyimide, polyamide, vinyl halidepolymers, vinylidene halide polymers, polyvinyl alcohol resins,ethylene-vinyl acetate copolymers, cellulose resins, polyvinyl butyralresins, and liquid crystal polymers. The liquid crystal polymers includepolyethylene terephthalate-p-hydroxybenzoic acid copolymer polyesters.

Of these polymers, preferred are those having excellent heat resistanceand moisture resistance, such as polyesters, e.g., polyethyleneterephthalate, polyethylene naphthalate, etc., and a polyethyleneterephthalate-p-hydroxybenzoic acid copolymer polyester liquid polymer.

The polarizing film according to the present invention can be producedby adding to the above-described organic polymer from 0.01 to 10% byweight, and preferably from 0.05 to 5% by weight, of the anthraquinonecompound of formula (I), i.e., a dichroic dye.

The anthraquinone compounds according to the present invention may beused either individually or in combinations of two or more thereof. Ifdesired, they may also be combined with other dichroic dyes, dyes havingno dichroism, or additives, such as ultraviolet absorbing agents,antioxidants, and the like.

The method for producing the polarizing film is not particularlylimited. In general, a composition comprising the film base polymer, theanthraquinone compound, and, if any, various additives is homogeneouslymelted and molded into a film or a sheet. The film or sheet isuniaxially stretched from 3 to 12 times at a temperature of from 20° to200° C. and then heat treated at a temperature of from 100° to 250° C.for a period of from 1 second to 30 minutes to obtain a film having athickness, for example, of from 30 to 200 μm. If desired, the film mayalso be stretched in the direction perpendicular to the major stretchingdirection.

The thus produced polarizing film can be used as such or, if desired,may be subjected to various finishing treatments depending on the finaluse. For example, a protective layer comprising a triacetate, acrylic,or urethane polymer, etc. may be laminated thereon, or a transparentconductive film comprising an indium-tin oxide, etc. may be formed onthe surface of the polarizing film by vacuum deposition, sputtering orcoating.

The present invention is now illustrated in greater detail withreference to Examples, but it should be understood that the presentinvention is not deemed to be limited thereto.

In these examples, the coefficient of dye orientation (Fdye) of theanthraquinone compound that is a dichroic dye was calculated by equation(1):

    Fdye=(D-1)/(D+2)                                           (1)

wherein D is an absorption dichroism ratio of a dichroic dye-containingfilm, which can be obtained from equation (2):

    D=Log (I.sub.0 /I.sub.II)/Log (I.sub.0 /I.sub.I)           (2)

wherein I₀ is a transmittance of a non-dyed film prepared under the samestretching conditions and the same treating conditions, and I_(I) andI_(II) each is a transmittane of the non-dyed film when a polarizingplane of an incident light ray is vertical to or parallel with thestretching axis, respectively. The Fdye value represents a degree oforientation of the dichroic dye. The greater the Fdye value, the greaterthe polarizing performance of the polarizing film.

EXAMPLE 1

One gram of an anthraquinone compound of formula: ##STR12## wasmelt-mixed with 1 Kg of a polyethylene naphthalate resin at 300° C., andthe mixture was moled into a film colored in distinct yellow.

The film was uniaxially stretched 5 times at 140° C. by means of astretching machine manufactured by T. M. Long to obtain a yellowpolarizing film having a thickness of 100 μm. The resulting polarizingfilm had a maximum absorption wavelength of 448 nm and a Fdye value of0.84.

The anthaquinone compound used in this example was synthesized asfollows.

A mixture consisting of 1 g of 1,5-bis(4'-aminophenylthio)anthraquinone,0.87 g of naphthalene-2,3-dicarboxylic acid anhydride, and 50 ml ofN,N-dimethylformamide was heated at 150° C. for 4 hours while stirring.After cooling, the precipitate formed was collected by filtration,washed with methanol, and dried to obtain 0.97 g of the desiredanthraquinone compound having a melting point of 300° C. or higher.

EXAMPLE 2

One gram of an anthraquinone compound of formula: ##STR13## wasmelt-mixed with 1 Kg of a polyethylene naphthalate resin, and themixture was molded into a film colored in distinct yellow.

The film was stretched in the same manner as in Example 1 to obtain a100 μm thick yellow polarizing film. The resulting polarizing film had amaximum absorption wavelength of 455 nm and a Fdye value of 0.85.

The anthraquinone compound used in this example was synthesized asfollows.

One gram of 1,5-bis(4'-aminophenylthio)anthraquinone was dissolved in100 ml of monochlorobenzene at 130° C., and to the solution was added4-n-butoxybenzoyl chloride prepared by reacting 1.02 g of4-n-butoxybenzoic acid and 0.77 ml of thionyl chloride. To the mixturewas further added 1.7 ml of pyridine, and the mixture was allowed toreact at 130° C. for 3 hours. After cooling, 100 ml of methanol wasadded to the reaction mixture, and the precipitated crystals werecollected by filtration to obtain 0.74 g of the desired compound havinga melting point of 300° C. or higher.

EXAMPLES 3 to 34

Anthraquinone compounds shown in Table 1 below were synthesized inaccordance with the process described in Example 1 or 2. A polarizingfilm was produced in the same manner as in Example 1, except for usingeach of these anthraquinone compounds. The maximum absorption wavelengthand Fdye value of the resulting polarizing film are also shown in Table1.

                                      TABLE 1                                     __________________________________________________________________________     ##STR14##                                                                                                                 Maximum                                                                       Absorption                       Example                                      Wavelength                       No.  R.sup.a                      R.sup.b    (nm)   Fdye                      __________________________________________________________________________          ##STR15##                   the same as R.sup.a                                                                      448    0.84                      2                                                                                   ##STR16##                   the same as R.sup.a                                                                      455    0.85                      3    NHCOC.sub.5 H.sub.11 (n)     the same as R.sup.a                                                                      450    0.82                      4    NHCOC.sub.3 H.sub.7 (n)      NHCOCH.sub.3                                                                             450    0.82                      5                                                                                   ##STR17##                   the same as R.sup.a                                                                      455    0.83                      6                                                                                   ##STR18##                                                                                                  ##STR19## 455    0.85                      7                                                                                   ##STR20##                   the same as R.sup.a                                                                      457    0.84                      8                                                                                   ##STR21##                   the same as R.sup.a                                                                      455    0.83                      9                                                                                   ##STR22##                   the same as R.sup.a                                                                      457    0.84                      10                                                                                  ##STR23##                   the same as R.sup.a                                                                      455    0.84                      11                                                                                  ##STR24##                   the same as R.sup.a                                                                      455    0.82                      12                                                                                  ##STR25##                   the same as R.sup.a                                                                      454    0.84                      13                                                                                  ##STR26##                   the same as R.sup.a                                                                      454    0.85                      14                                                                                  ##STR27##                   the same as R.sup.a                                                                      454    0.84                      15                                                                                  ##STR28##                   the same as R.sup.a                                                                      455    0.85                      16                                                                                  ##STR29##                   the same as R.sup.a                                                                      455    0.85                      17                                                                                  ##STR30##                   the same as R.sup.a                                                                      457    0.84                      18                                                                                  ##STR31##                   the same as R.sup.a                                                                      455    0.84                      19                                                                                  ##STR32##                   the same as R.sup.a                                                                      455    0.83                      20                                                                                  ##STR33##                   the same as R.sup.a                                                                      455    0.84                      21                                                                                  ##STR34##                   the same as R.sup.a                                                                      448    0.83                      22                                                                                  ##STR35##                   the same as R.sup.a                                                                      447    0.82                      23                                                                                  ##STR36##                   the same as R.sup.a                                                                      448    0.82                      24                                                                                  ##STR37##                   the same as R.sup.a                                                                      448    0.82                      25                                                                                  ##STR38##                   the same as R.sup.a                                                                      447    0.83                      26                                                                                  ##STR39##                   the same as R.sup.a                                                                      447    0.80                      27                                                                                  ##STR40##                   the same as R.sup.a                                                                      447    0.83                      28                                                                                  ##STR41##                   the same as R.sup.a                                                                      447    0.84                      29                                                                                  ##STR42##                   the same as R.sup.a                                                                      446    0.81                      30                                                                                  ##STR43##                   the same as R.sup.a                                                                      446    0.82                      31                                                                                  ##STR44##                   the same as R.sup.a                                                                      446    0.82                      32                                                                                  ##STR45##                   the same as R.sup. a                                                                     447    0.82                      33                                                                                  ##STR46##                   the same as R.sup.a                                                                      447    0.82                      34                                                                                  ##STR47##                   the same as R.sup.a                                                                      447    0.83                      __________________________________________________________________________

EXAMPLE 35

One gram of an anthraquinone compound of formula: ##STR48## wasmelt-mixed with 1 Kg of a polyethylene naphthalate resin, and themixture was molded into a film colored in distinct yellow.

The film was uniaxially stretched 5 times at 140° C. by means of astretching machine manufactured by T. M. Long to obtain a yellowpolarizing film having a thickness of 100 μm. The resulting polarizingfilm had maximum absorption wavelengths of 576 nm and 603 nm and a Fdyevalue of 0.83.

The anthaquinone compound used in this example was synthesized asfollows.

Three grams of 1,5-diamino-4,8-bis(4'-aminophenylthio)anthraquinone weredissolved in 100 ml of N-methylpyrrolidone. To the solution was added1.7 g of benzoyl chloride at 22° to 25° C., and 2 g of pyridine wasfurther added thereto, followed by stirring at 22° to 25° C. for 4hours. The reaction mixture was poured into 100 ml of methanol, and theprecipitate formed was collected by filtration and dried to obtain 3.5 gof the desired compound having a melting point of 300° C. or higher.

EXAMPLE 36

One gram of an anthraquinone compound of formula: ##STR49## wasmelt-mixed with 1 Kg of a polyethylene naphthalate resin, and themixture was molded into a film colored in distinct blue.

The film was uniaxially stretched 5 times at 140° C. by means of astretching machine manufactured by T. M. Long to obtain a bluepolarizing film having a thickness of 100 μm. The resulting polarizingfilm had maximum absorption wavelengths of 573 nm and 604 nm and an Fdyevalue of 0.75.

The anthraquinone compound used in this example was synthesized asfollows.

A mixture consisting of 3.5 g of1,5-diamino-4,8-bis(4'-aminophenylthio)anthraquinone, 2.9 g ofnaphthalene-2,3-dicarboxylic acid anhydride, and 400 ml ofN,N-dimethylformamide was heated at 150° C. for 4 hours while stirring.After cooling, the precipitate was filtered, washed with methanol, anddried to obtain 4.0 g of the desired compound having a melting point of300° C. or higher.

EXAMPLES 37 to 70

Anthraquinone compounds shown in Table 2 were prepared in the samemanner as described in Example 35 or 36. A polarizing film was producedin the same manner as in Example 35, except for using each of theanthraquinone compounds of Table 2. The maximum absorption wavelengthand Fdye value of the resulting polarizing film are also shown in Table2.

                                      TABLE 2                                     __________________________________________________________________________     ##STR50##                                                                                                                  maximum                                                                       absorption                      Example                                       wavelength                      No.  R.sup.a                      R.sup.b X   (nm)  Fdye                      __________________________________________________________________________    35                                                                                  ##STR51##                   the same as R.sup.a                                                                   NH.sub.2                                                                            576 603                                                                           0.83                      36                                                                                  ##STR52##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 604                                                                           0.75                      37   NHCOC.sub.4 H.sub.9 (n)      the same as R.sup.a                                                                   NH.sub.2                                                                            573 0.78                                                                      603                           38   NHCOC.sub.5 H.sub.11 (n)     NHCOCH.sub.3                                                                          NH.sub.2                                                                            573 0.78                                                                      603                           39   NHCOC.sub.3 H.sub.7 (n)      the same as R.sup.a                                                                   H     545 0.78                      40                                                                                  ##STR53##                   the same as R.sup.a                                                                   NH.sub.2                                                                            576 606                                                                           0.82                      41                                                                                  ##STR54##                   the same as R.sup.a                                                                   H     544 0.79                      42                                                                                  ##STR55##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 606                                                                           0.83                      43                                                                                  ##STR56##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 605                                                                           0.79                      44                                                                                  ##STR57##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 605                                                                           0.82                      45                                                                                  ##STR58##                   the same as R.sup.a                                                                   H     545 0.75                      46                                                                                  ##STR59##                   the same as R.sup.a                                                                   NH.sub.2                                                                             573 605                                                                          0.80                      47                                                                                  ##STR60##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 606                                                                           0.83                      48                                                                                  ##STR61##                   H       NH.sub.2                                                                            573 605                                                                           0.63                      49                                                                                  ##STR62##                   the same as R.sup.a                                                                   NH.sub.2                                                                            572 605                                                                           0.80                      50                                                                                  ##STR63##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 607                                                                           0.81                      51                                                                                  ##STR64##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 606                                                                           0.81                      52                                                                                  ##STR65##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 605                                                                           0.81                      53                                                                                  ##STR66##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 606                                                                           0.78                      54                                                                                  ##STR67##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 607                                                                           0.82                      55                                                                                  ##STR68##                   the same as R.sup.a                                                                   H     544 0.76                      56                                                                                  ##STR69##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 605                                                                           0.80                      57                                                                                  ##STR70##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 604                                                                           0.74                      58                                                                                  ##STR71##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 604                                                                           0.74                      59                                                                                  ##STR72##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 605                                                                           0.74                      60                                                                                  ##STR73##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 604                                                                           0.75                      61                                                                                  ##STR74##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 604                                                                           0.74                      62                                                                                  ##STR75##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 603                                                                           0.72                      63                                                                                  ##STR76##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 0.76                      64                                                                                  ##STR77##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 605                                                                           0.76                      65                                                                                  ##STR78##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 603                                                                           0.74                      66                                                                                  ##STR79##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 604                                                                           0.76                      67                                                                                  ##STR80##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 604                                                                           0.76                      68                                                                                  ##STR81##                   the same as R.sup.a                                                                   H     544 0.73                      69                                                                                  ##STR82##                   the same as R.sup.a                                                                   NH.sub.2                                                                            574 604                                                                           0.75                      70                                                                                  ##STR83##                   the same as R.sup.a                                                                   NH.sub.2                                                                            573 604                                                                           0.75                      __________________________________________________________________________

Since the anthraquinone compounds according to the present inventionexhibit satisfactory compatibility with organic polymers to be used asfilm base materials as well as high dichroism, the polarizing filmsproduced from these compounds are excellent in all respects required,i.e., polarizing performance, heat resistance, moisture resistance,weather resistance, and transparency.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. An anthraquinone compound represented by formula:##STR84## wherein two R, which may be the same or different, eachrepresents a hydrogen atom, --NHCOR¹, or --CONHR¹, wherein R¹ representsan alkyl group, a substituted or unsubstituted aryl group, or asubstituted cycloalkyl group; and two X, which may be the same ordifferent, each represents a hydrogen atom or an amino group, providedthat X and R are not simultaneously a hydrogen atom.
 2. An anthraquinonecompound as claimed in claim 1, wherein R¹ represents a straight chainor branched alkyl group having from 1 to 8 carbon atoms, a phenyl group,a phenyl group substituted with an alkyl group having from 1 to 8 carbonatoms, a phenyl group substituted with an alkoxy group having from 1 to8 carbon atoms, a biphenyl group, a heterocyclic group, a naphthylgroup, an anthraquinon-2-yl group, an alkylcarbonylamino-substitutedphenyl group, an arylcarbonylamino-substituted phenyl group, a4-cyclohexylphenyl group, a cyclohexylphenyl group substituted with atrans-4-alkyl group having from 1 to 8 carbon atoms, a cyclohexyl group,a cyclohexyl group substituted with a trans-4-alkyl group having from 1to 8 carbon atoms, or a 4-cyclohexylcyclohexyl group.
 3. The compound ofclaim 2 wherein R' represents a straight chain or alkyl group havingfrom 1 to 8 carbon atoms.